1. Field of the Invention
The present invention generally relates to exhaust systems for land vehicles. More specifically, the present invention relates to an improved exhaust system layout for snowmobiles that reduces temperature increases in the associated exhaust systems.
2. Description of the Related Art
Snowmobiles are powered by internal combustion engines that are mounted to a frame assembly within a substantially enclosed engine compartment. The engine compartment typically is defined within a portion of a body panel (also mounted to the frame assembly) such that direct airflow through the engine compartment is inhibited.
An exhaust system mounts to the frame assembly and to the engine for routing exhaust byproducts from the engine to the atmosphere. Generally, the exhaust system mounts to a forward-facing portion of the engine and extends forward before wrapping around one side of the engine.
Due to the restricted air flow within the engine compartment, the amount of cooling provided by the air entering the engine compartment is greatly reduced. Thus, the temperatures of the exhaust system components tend to be very high. The increased temperatures result in increased heat transfer from the exhaust system to a variety of other components adjacent the exhaust system, e.g., to the snowmobile frame assembly. Heat transfer to the frame assembly and other nearby components can cause such components to reach very temperatures. For many reasons, such high temperatures are not desired.
Thus, a snowmobile arrangement that can provide increased cooling to an exhaust system, which will reduce the amount of heating of components adjacent the exhaust system, is desired. Additionally, the exhaust system and surrounding structures preferably are simply constructed and admit of a rather simple cooling arrangement.
Accordingly, one aspect of the present invention involves a snowmobile comprising a frame assembly, an engine, a drive belt, and exhaust system, and an exhaust system cooling passage. The frame assembly includes a forward portion and an inverted generally U-shaped portion. The engine is mounted to the forward portion of the frame assembly. The drive belt is powered by the engine and is disposed at least partially within the inverted generally U-shaped portion. The exhaust system is connected to the engine and extends rearwardly of the engine in a region defined between the inverted generally U-shaped portion and the drive belt. The exhaust cooling passage is defined between the forward portion of the frame assembly and the rear of the snowmobile. The exhaust system cooling passage is located adjacent at least a portion of the exhaust system.
Another aspect of the present invention involves a snowmobile that comprises a frame assembly, an engine, a seat, an exhaust system, and a resilient seat mount. The frame assembly comprises a forward portion and an inverted generally U-shaped portion. The engine is mounted to the forward portion of the frame assembly. The seat is coupled with the U-shaped portion of the frame assembly. The exhaust system is connected to the engine and extending rearwardly of the engine in a region defined below the seat to a silencer box positioned generally below the seat. The resilient seat mount is positioned between the silencer box and the seat. The resilient seat mount is configured to reduce heat transfer between the silencer box and the seat.